Cold Cranking Amps oddity

[awemawson]

Yesterday I went to do some work on my 'New to Me' Ford 4600 tractor - only had it a few days so much of it is an unknown quantity. It's been a very good starter, on the button each time and much better than my Ford 4000 (which is basically the same engine)

This time just a slight click and nowt else. Battery flat as a fluke - blast must have left something like a light on un-noticed. Fortunately a friend was with me to help lift the battery out as it's an unbelievably heavy lump.

[awemawson]

Dragged it into the welding shop to put it on charge, but my fancy modern battery charger wouldn't put anything into it at all. Battery volts were 11.5.

Dug out my old and simple 'non-smart' battery charger which is only rated at 6 amps, but it only shoved 3 amps in on charge. Presumably something a bit high resistance in the battery - bit of sulphation or what ever.

After a few minutes charging I discharged it a bit with an old WW2 Aldis lamp (5 amps at 12 volts) then it started charging at a much more sensible rate, but still the modern charger was no use.

Left it charging for several hours and then dug out my 'Cold Cranking Amps' tester. This has proved invaluable over the years I've had it to sort useless from good batteries.

Now the oddity. Quite repeatably, if I measured cold cranking amps having just taken the battery off charge I got something like 450 (should be 880) BUT if I discharged the battery for a few minutes the cold cranking amps rose to 550 if tested with load removed.

[awemawson]

Now I don't know how that tester works - obviousy somehow it's measuring the internal resistance of the battery and deriving CCA from that. Googling tells me there are several methods including testing using short duration high current pulses and and other way is using AC across a range of frequencies.

However it works, as I say it has proved over time to be a reliable and consistent tool.

Now the good news is having gone through a few charge / discharge cycles (only slight discharge for maybe ten mins at 5 amps) the battery was able to be charged using the fancy modern charger and was left over night charging until all cells were lightly gassing.

The even better news is that I now am measuring a CCA of 900 amps - (battery is rated 880) 

[awemawson]

Being single handed today, refitting the battery involved some nifty driving with the fork lift truck (how ever did I manage without it).

So battery gets re-installed - checked for discharge when everything is supposedly turned off (none) and low and behold the engine springs into life at the first jab of the starter - just as it was. Battery volts monitored when engine on fast tick over - they rise to 14v - so the alternator is charging ok.

But the question remains - why did the CCA seem to rise after discharge and return to the lower value after charging during the process even though eventually rising to the correct figure. My guess is that there was light sulphation on the plates which was eventually removed by what I did and maybe this was influencing things.

[hermetic]

Hi Awemawson, If the battery has been stood, suphation occurs on the plates, and this insulates the plates from the electrolyte. Putting a reasonably heavy discharge on the battery will destroy the sulphate layes, so the battery can then deliver more current. Problem is that some of the sulphate will not be reconverted into lead and will sink to the bottom of the battery, so you have lost some of the "ultimate chemical capacity" of the unit The old style fork lift batteries used to be put on a heavy discharge cycle once or twice a year to prevent this. As to the CC ammeter, I am shocked that you have not pulled it to bits to see how it worked;-)
Phil

[awemawson]

Phil, it had undoubtedly stood unused for several months prior to coming into my ownership as the previous owner passed away and the family organised disposal. However when I first saw the tractor it started on the button from stone cold, and when delivered to me was the same. It's been here a few days and each time I've needed to shift it it's been a sterling starter, I think I probably left something turned on that flattened the battery overnight - the electrics are the usual nightmare of added bits and bits broken that may or may not still be connected. So I don't think it's been heavily sulphated. Also looking at the battery it's probably not much more than a year old. Just as well it's come back to life - those batteries cost a kings ransom 

[vtsteam]

Back in the old days (early 70's  ) when experimenting with windspinners etc. one way of obtaining usable batteries with little cash for new or deep cycle batts was to use junkyard auto batteries discarded because they could no longer crank a car in winter.

The secret to rejuvenation was to empty out the old electrolyte, and rinse a few times with distilled water to remove accumulated sulphation sediment on the bottom of the plates, drain and refill with clean battery acid, or at least settled and drawn off clear. They then worked, not as good as new, but certainly as good usable batteries, in most cases. This can't cure plate damage, but it can bring the lower portion of the plate back into service where it is masked or shorted by accumulated conductive sediment, and that is a frequent ill of old or neglected batteries.

Charging stirs up old sediment and temporarily can clear the lower plate section -- if it will accept a charge at all. Sometimes to clear a some buildup the battery is charged for longer than its normal amount of time -- some marine inverter/chargers do this automatically for a specific interval -- I had a Heart Interface inverter that did this when I lived aboard.

I don't know why the battery in question increased its CCA after some discharge, but perhaps more sediment was stirred up by the discharge rate imposed after initial charging. One thing is certain, if there is sediment present, gravity works to re-deposit it on the bottom. The problems may return, particularly if the tractor sits for awhile and unpredictably, depending on how much "stirring there is, what the sediment looks like and how it arranges itself.

I have several chargers, and the newer "smart" charger is basically useless. It is stupider than the dumb ones and refuses to do its job unless conditions are perfect. Ahhh progress: smart everything, and made of plastic!

[hermetic]

Hi Awemawson, yes that is a bit mysterious, a small discharge will cause sulphation wheras a heavy one usually will remove it. but you checked the tractor with everything off, and there was no current flow? odd indeed. Try disconnecting one of the terminals from the battery and put a sidelight bulb between the battery terminal and the lead, and see if it glows. It could be that when you moved the tractor something got disturbed and is flattening the battery slowly. leaky diodes in the alternator, does the charge light work/is it glowing when all is off? Was it stood under cover or exposed? I know what you mean about tractor batteries, I recently bought a new one for my Fordson diesel major. I leave it with a cheapo Lidl anti frost maintaining charger on it, and it is kept in a nice warm shed, covered with all sorts of junk to keep it warm, and almost never used, but the day is coming...........................
Phil

[awemawson]

Better than the side light bulb was my trusty Avo on the amps range - no discharge and no leakage 

[lordedmond]

Hope its a mark 8

last time I looked on RS at them had to sit down quick and have a large Brandy

worst of all my one sticks so I cannot trust it

can you still get the larger cell for the ohms range the lower one is easy

Stuart

[awemawson]

Steve, some years ago I had a little 'works truck' that had a 24v bank of fork lift cells under the load space as the power source. When I got it the cells were fairly sulphated, and although improved by a few charge / discharge cycles were in a bad way. I drained and replaced the H2SO4 having done as you suggested and rinsed what would come from the bottom. I bought a little device that self powered off the battery shocked it at intervals with a high voltage high energy pulse. Nowadays this same technique is employed in 'battery maintainers' that you can buy for laying up cars.

After a week of this treatment I got the batteries back to 95% of their rated capacity. I made a dummy load from a length of heavy galvanised fence wire wrapped around a bit of asbestos flue, and tuned to the correct resistance for a 10 hour discharge - even rigged up a chart recorder to plot the voltage under discharge. An entirely satisfactory result. Used the truck for many years and it held charge and worked fine.

I still have the little 'shocker box' awaiting repair. I stupidly put it across a battery with wrong polarity and it wasn't much amused 

[Pete W.]

Hi there, Andrew and Stuart.

Andrew, maybe if you canvas a few airlines, you'll find one that'll do you a swap for a nice Lithium Ion battery!          

Stuart, the 1.5 volt cell (U2 to oldies like me, aliter D-size) ought still to be available.  I think you were referring to the 15 volt battery that's used on the high Ohms range.  I did manage to buy one a couple of years ago.  Also, there used to be a mini DC-to-DC converter (from a third-party supplier) that tapped off the 1.5 volt cell and produced the necessary 15 volts.  I haven't seen any reference to those for decades.  It was never very clear to me how you switched the converter on and off - maybe some modification to the AVO wiring was required.

I bought my AVO 8 Mk 2 for £32 10s 0d from Watts' Radio in the Apple Market, Kingston upon Thames, still got the receipt somewhere!   

[awemawson]

I know what you mean about tractor batteries, I recently bought a new one for my Fordson diesel major. I leave it with a cheapo Lidl anti frost maintaining charger on it, and it is kept in a nice warm shed, covered with all sorts of junk to keep it warm, and almost never used, but the day is coming...........................
Phil

The Diesel Major is usually a very good starter. One trick is a rope wrapped around the flat belt side pulley (if you have one) and just pull start it like a lawn mower! Just make sure it's out of gear or you may not get to do it twice. Mine was happy with an old battery out of my Landrover - and it didn't even have a charging set up. The generator was fitted but not wired up. Just put it on charge every few months.

[lordedmond]

Pete

Yes that's the one real odd voltage weren't they

The old D type   

I still have it for but it's not used

I now use a fluke for the bits I do now

But that mk 8 was the job for tuning rf circuits for a dip and peak digital do dahs do not cut it

Anyway let's not take Andrews thread OT

Stuart

[dsquire]

Andrew

When I lived in Northern Ontario winter temperature dropped way below 0. When the temp was at the extreme we would turn the headlights on for a minute before trying to start the car. Now turn the light off and wait another minute then hit the starter. If the car isn't running in 30 seconds then you are probably going to need a boost to get started.

When you initially discharged the battery this would cause heat. Now that the battery is warmed up you will get a higher reading and more cold cranking power. 

Cheers 

Don

[awemawson]

Anyway let's not take Andrews thread OT

Stuart

Why ever not - I'm more guilty than most 

[DavidA]

If I remember rightly the way to deal with discharged batteries is to drain of the electrolyte,  Refill wit battery acid that has a Specific Gravity (SG) of 1250.  re4charge and then check the SG again.  If it isn't 1250, do the drain routine and refill again with 1250 acid.

Repeat until the SG is 1250 after the charging process.

Hope I've got that right.

Dave.

[hermetic]

Hi Andrew, No, unfortunately I haven't got the pulley on the Fordson but I do have an AVO 8. A real engineers multimeter!! To Stuart, Yes you can still get the batteries for the high ohms range, they are on ebay.

http://www.ebay.co.uk/sch/i.html?_trksid=p2050601.m570.l1313.TR2.TRC1.A0.H0.XAVO+battery&_nkw=AVO+battery&_sacat=0&_from=R40

Phil
East Yorks

[awemawson]

Shame - I gave a spare one away when I sold my Major recently - you could have had it buckshee

[vtsteam]

Never heard of buckshee before. It means free?

[awemawson]

Yes

I believe it comes from the Arabic / Persian backsheesh (sp) which is a tip or gratuity. Land at Cairo airport and the air is full of the word.

I suppose it's a bit more of our Colonial Heritage. 

BTW the tax is still due on that tea you dumped in Boston Harbour 

[vtsteam]

Well it was Englishmen doing the dumping, don't forget! A change in implementing what was in fact a tax reduction plus the addition of a colonial representative in parliament, and Starbucks would be serving mostly tea now, under a different flag! 

[awemawson]

Well it was Englishmen doing the dumping, don't forget! A change in implementing what was in fact a tax reduction plus the addition of a colonial representative in parliament, and Starbucks would be serving mostly tea now, under a different flag! 

...mmm not quite my understanding. It was rebellious colonists who dumped the tea as I was taught in school very many years ago, and wiki seems to back me up:

http://en.wikipedia.org/wiki/Boston_Tea_Party

[vtsteam]

Yes Andrew, but weren't they still British subjects, primarily English extraction, retaining citizenship, and flying the British flag at the time, despite increasing disaffection? And wasn't it that they wanted closer ties -- acknowledgement as citizens through representation in Parliament that caused the rift? Rather than the tea tax itself.

Perhaps I have it wrong -- had  British colonists been severed from citizenship because of their relocation to America at some earlier point in time?  If so then America existed as a foreign national entity much earlier than the revolution.

I was taught what you were Andrew, in school. But much of that I later learned was simplistic.

[awemawson]

No idea about the citizenship issue. I had assumed as they had upped sticks and left home for a new life they'd effectively revoked any such ties, but that's just me assuming ! After all the Pilgrim Fathers took to the boats to escape religious persecution as I understand it, so weren't too bothered about 'the old country'

 . . . now just pay up the outstanding taxes (with interest) and you can have as many seats in the European Parliament that you want